The skeleton is the structure of human body. The human skeleton consists of many bones of different sizes, long , short , flat, etc. It gives a specific shape to the human body and protects the soft parts of the body like brain , lungs , heart , stomach , intestines etc. from external aggression. The external skeletal system refers to the hairs , teeth , nails, etc. and the internal skeletal system mainly refers to the internal structures of the body such as bones , cartilage , cartilage etc.